10/1/2008: If a creature with banding attacks, it can team up with any number of other attacking creatures with banding (and up to one nonbanding creature) and attack as a unit called a "band." The band can be blocked by any creature that could block a single creature in the band. Blocking any creature in a band blocks the entire band. If a creature with banding is blocked, the attacking player chooses how the blockers' damage is dealt.
10/1/2008: A maximum of one nonbanding creature can join an attacking band no matter how many creatures with banding are in it.
10/1/2008: Creatures in the same band must all attack the same player or planeswalker.
10/1/2008: If a creature with banding blocks, the defending player chooses how the blocked creature deals its combat damage. Creatures don't form "bands" on defense.